This made it completely plausible that Aaron’s Gamertag was from his Xbox One and migrated over to his Xbox Series X or S account.
Avengers: Endgame was released in 2019, which was about a year after Sony allowed Fortnite to cross-platform play with Xbox and other gaming devices.
I originally assumed the easter egg was cute, but invalid, because Korg played Fortnite on a PlayStation 4 in Avengers: Endgame, but that may not be the case.
He also could’ve been a PS4 owner a couple of years ago and decided to make a switch.